A popular type of toy building block is one that has flat surfaces, such as a cube, which can be stacked upon other blocks of like design. Structures made with this type of block are very unstable and can be toppled with the slightest of disturbances. These blocks must also be carefully balanced upon one another, thus limiting the manner in which they can be stacked.
Another popular type of toy building block are LINCOLN LOG building blocks which have transverse notches. The logs are stacked by engaging the notched sections of adjacent logs. These types of blocks can be stacked in only a very limited set of alignments.
Another popular type of toy building block are LEGO building blocks which have a pattern of projections on the top, and recesses on the bottom for engaging the projections. These types of blocks are stacked upon one another by pressing the projections of one block into the recesses of another. These blocks can be stacked together in a limited number of predetermined locations dictated by the pattern of projections and recesses.
There is a need for further building blocks that can be securely and releasably attached together for building relatively stable structures.